Fuse construction



March 14, 1950 H. v. DRYER FUSE CONSTRUCTION Original Filed Feb. 26, 1948 J JJMZNTOR.

r By 6277 x7e )Zlornq Pa tented Mar. 14, 1950 FUSE CONSTRUCTION Henry V. Dryer, Milwaukee, Wis assignor to McGraw Electric Company, a corporation of Delaware Original application February 26, 1948, Serial No.

11,132, now Patent No. 2,490,950, dated December 13, 1949.

Divided and this application March 4, 1949, Serial No. 79,668

4 Claims. (Cl. 200-421) 1948, for Fuse constructions, which is assigned to the same assignee as the present application, and which has resulted in Patent No. 2,490,950, dated Dec. 13, 1949.

Objects of this invention are to provide a cartridge type of fuse construction in which an outer opaque cylinder is provided and is equipped with transparent means arranged to give a view of the internally positioned fuse link to ascertain the condition of the fuse link, and in which the transparent means includes a part, at least, of clear acrylic plastic such as Lucite, and in which this plastic material is located closely adjacent the fuse link and constitutes a discolorable member which will indicate when the fuse has blown so that the cartridge may be discarded and a new cartridge substituted. I

Further objects are to provide a cartridge type fuse construction employing a plastic transparent indicating member in .which the cartridge is closed at both ends and is provided with are extinguishing material located adjacent the plastic member and with granular material on opposite sides of the arc extinguishing material to provide a cooling and expansion chamber or surface for the gases, the arc extinguishing material being designed to give on water vapor and chill the arc and aid in the extinguishing thereof.

An embodiment of the invention is shown in the accompanying drawings, in which- Figure 1 is a sectional view through the device.

Figure 2 is a sectional view on the line 2-2 of Figure 1.

Referring to the drawings, it will be seen that an opaque insulating casing or tube l is provided with a threaded aperture 2 into which a transparent plug 3 is screwed. This plug is preferablv provided with a slot 4 for a screw driver and if desired, it may be formed of a clear acrylic plastic or any other suitable transparent material. Substantially centrally of the casing i a trans parent cylindrical member 5 of clear acrylic plastic, such as Lucite, is positioned. This cylindrical member 5 is provided with a central aperture 6 through which the fuse link I extends. Fiber or other suitable washers 8 are located on onposite sides of the cylindrical member 5. Powdered bauxite 9 is also positioned on opposite sides of the cylindrical member 5 but beyond the washers 8. Sand i0 is positioned beyond the bauxite. The transparent screw threaded plug 3 allows the inspector to view the condition of the 2 transparent acrylic plastic member 5. When the fuse link is ruptured discoloration of the interior of the cylindrical member 5 takes place and such condition is observable through the transparent plug 3 from the outside of the opaque casing i.

Opposite ends of the fiber or other insulating casing l are threaded and receive the terminal caps II and I2. One end of the fuse link I is passed through an aperture in a metal disk I: and is soldered thereto as indicated at l4. A dished cup-like metal member I5 is positioned between the end cap l2 and the disk l3, and preferably a yielding gasket I6 is positioned between the disk l3 and the end of the casing I. At the opposite end of the casing a fitting having a disklike portion l1 and a tubular inwardly projecting extension [8 and a tubular threaded outwardly projecting extension I9 is positioned. This member is of metal and passes through an aperture in the end cap H and is locked in place by means of a nut 20. The fuse link passes through the tubular extensions i8 and I9 and is soldered as indicated at 2 l'. the solder closing the opening through the extension IS. A yielding gasket 22 is positioned between the end cap H and the end of the insulating casing I.

The washers 8 prevent the powdered bauxite from seeping into the space between the transparent cylindrical member 5 and the transparent plug 3. The transparent plug 3 may be either out of contact with the cylindrical member 5 or may be in contact therewith, as desired.

The operation of this apparatus is as follows. Fusing of the fuse link 1 causes discoloration of the plastic cylinder which is viewable from the outside of the device, as described, and causes liberation of water vapor from the bauxite 9 which assists in extinguishing the arc and cooling the hot vapors, and also assists in cooling the sand l0.

It has been found that rupturing of the fuse link almost always occurs centrallv thereof. Also it has been found that when the fuse link is ruptured the sand provides expansion chambers and a very extensive condensing surface for the gases. Also it is to be noted that the bauxite liberates a quantity of water vapor as previously descr bed with its chilling and cooling effect. Consequently the pressure within the closed cartridge type of fuse, as described, does not rise to a dangerous extent even on heavy overloads.

It will be seen that a simple type of cartridge type fuse construction has been provided by this invention which is eminently practical and which,

although the casing is formed of opaque ma- 3 terial, nevertheless is provided with dlscolorable transparent means and allows for external inspection with consequent determination of the condition of the fuse link.

It is intended that whenever one of these fuse devices blows, that it shall be removed and a new cartridge fuse substituted therefor.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

1. A cartridge type fuse construction comprising a tubular outer casing of opaque material having an opening intermediate its ends, a transparent plug screwed into said opening, a clear acrylic plastic cylinder located within said casing adjacent said transparent plug, terminals adjacent the opposite ends of said casing, and a fuse link electrically connecting said terminals and extending through said casing and through said plastic cylinder.

2. A cartridge type fuse construction comprising a tubular outer casing of opaque material having an opening intermediate its ends, a transparent plug screwed into said opening, a clear acrylic plastic cylinder located within said casing adjacent said transparent plug, terminals adjacent the opposite ends of said casing, a fuse link electrically connecting said terminals and extending through said casing and through said plastic cylinder, powdered bauxite located adjacent the sides of said plastic cylinder and within said "casing, and sand within said casing and located on opposite sides of said bauxite.

3. A cartridge type fuse construction comprising a tubular outer casing of opaque material having an opening intermediate its ends, a clear acrylic plastic member located within said casing adjacent said opening, terminals adjacent opposite ends of said casing, a fuse link electrically connecting said terminals and extending through said casing and in close proximity to said plastic member, powdered material on opposite sides of said plastic member having the characteristics oi evolving water vapor upon rupture of said fuse link, and washers on opposite sides of said plastic member arranged to prevent the seepage of said powdered material to a position between said plastic member and said casing.

4. A cartridge type fuse construction comprising a tubular outer casing of opaque material having an opening intermediate its ends, a transparent plug screwed into said opening, a clear acrylic plastic cylinder located within said casing adjacent said transparent plug, terminals adjacent the opposite ends of said casing, a fuse link electrically connecting said terminals and extending through said casing and through said plastic cylinder, powdered bauxite located adjacent the sides of said plastic cylinder and within said casing, sand within said casing and located on opposite sides of said bauxite, and washers on opposite sides of said plastic cylinder arranged to prevent seepage of bauxite into the space between said plastic cylinder and said casing.

HENRY V. DRYER.

No references cited. 

